1. Technical Field
The present disclosure relates to an intercom system and a communication method thereof.
2. Description of the Related Art
Recently, an intercom system has been widely used in a house and the like. The intercom system is configured by, for example, a slave device (referred to as “an entrance slave device” below) and a master device (referred to as “an intercom master device” below). The slave device is installed at an entrance on the outside of a house, and has a camera attached thereto. The master device is installed in the house, and displays an image captured by the camera of the entrance slave device, on a monitor. A monitor (referred to as “an additional monitor” below) may be additionally installed in the intercom system.
Generally, in the intercom system, the entrance slave device and the intercom master device are connected to each other by using a two-wire cable. The intercom master device and the additional monitor are connected to each other by using a two-wire cable. The publication of Japanese Patent Unexamined Publication No. 2007-124227 discloses an intercom system in which packets are transmitted and received between an entrance slave device and an intercom master device which are connected to each other by using a two-wire cable.